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Countryside Council for Wales
Landscape & wildlife
Please note - A new body, Natural Resources Wales has taken over all functions and services previously carried out by Countryside Council for Wales. While the Natural Resources Wales website continues to be developed, some online services will continue to be provided on this web site.

Dyffrynnoedd Nedd a Mellte, a Moel Penderyn

Dyffrynnoedd Nedd a Mellte, a Moel Penderyn is
of special interest for both geodiversity and biodiversity.
Dyffrynnoedd Nedd a Mellte, a Moel Penderyn is special for its
extensive and diverse semi-natural woodland, important populations
of several flowering plants and supporting outstanding assemblages
of mosses, liverworts and lichens. The old quarry faces and rock
outcrops in the vicinity of Pontneddfechan provide excellent
exposures of Carboniferous rocks. These range in age from about 325
million to about 315 million years old and detail the changes in
environment within a river delta setting. The very bottom layers of
the South Wales Coal Measures are exposed here. At Craig y Ddinas
and Moel Penderyn a number of faults (cracks along which movement
has occurred) and folds can be seen in the rock. The faults, which
extend along the Vale of Neath, have been active since
Carboniferous times and movement along them continues to cause
small earthquakes today. The Mellte and Hepste rivers provide an
exceptional example of how geology controls the paths of rivers and
the shape of their valley. The numerous waterfalls generally occur
when the river crosses a fault, from hard sandstone to softer
mudstone.

Managing this site

The Forestry Commission and the Brecon Beacons National Park
Authority own parts of this site. The remainder is under private
ownership. The special features of this SSSI and CCW’s views about
site management have been summarised in a Site Management
Statement, addressed to the owners and managers of the land. The
statement can be found in the resource section below.

Access information

Large sections of this site are designated CROW access land.
Other sections are accessible via public footpaths. For detailed
maps and information regarding access visit our access map via the
resource section below.

Other information

A large part of the site is included in Coedydd Nedd a Mellte
Special Area of Conservation. The meaning is ‘the valleys of Nedd
and Mellte and Moel Penderyn’ with dyffrynnoedd the plural of
dyffryn ‘valley’. The meaning of the river name Nedd is uncertain
but ‘shining’ or simply ‘river’ have been suggested. Nedd is almost
certainly related to the river name Nidd in Yorkshire. The river
name Mellte is also difficult; the river is notable for its
unpredictable flow, rocky course and waterfalls and may be
connected to mellt ‘lightening’. Mellteu, however, occurs as the
name of one of the daughters of Brychan Brycheiniog and the river
name may belong to a class of streams and rivers that have been
given personal names. Penderyn means ‘bird’s head’ from pen ‘head’
and deryn ‘bird’; Penderyn, probably refers to some apparently
bird-like topographical feature such as Moel Penderyn. Moel as a
feminine singular noun means ‘treeless hill, hilltop’.